1. Field of the Invention
The present invention relates to a cleaning device for an image forming apparatus such as a copying machine, a laser printer, or a facsimile, and more specifically, it relates to a toner recovering device that conveys and recovers toner.
2. Description of the Related Art
Image forming apparatuses are provided with a toner recovering device that removes and recovers residual toner on an image bearing member such as a photosensitive member or an intermediate transfer member. This toner recovering device includes a cleaning member that removes residual toner on the image bearing member, a recovered toner container that contains residual toner removed by the cleaning member, and a conveying unit that conveys residual toner to the recovered toner container. The conveying unit conveys recovered toner with a screw having a spiral shape, along the conveying path to the recovered toner container.
However, the flowability of toner conveyed by the conveying screw of the conveying unit decreases significantly due to commingling of paper debris or depending on temperature and humidity. If the flowability of toner being conveyed is low, toner is deposited and agglomerated in the vicinity of the screw, and a toner clog occurs in the conveying path. In addition, if the flowability of toner being conveyed is low, the recovered toner is attached to the surface of the spiral blade of the conveying screw. This attachment decreases the conveying capacity of the conveying screw and causes a toner clog in the recovered toner conveying mechanism. If a toner clog occurs in the conveying path, the load on the drive system that drives the conveying unit increases, and the inside of the apparatus is contaminated.
In order to prevent the deposition of toner, a ball is used as discussed in Japanese Patent Laid-Open No. 7-92875 and Japanese Patent Publication No. 3-18713. Specifically, in order to prevent the deposition of toner in the vicinity of an opening through which toner is sent to a conveying screw, a ball is disposed in the opening.
However, toner can be deposited not only in the opening but also on the conveying screw. Also, in such a case, a toner clog occurs. Particularly in the case of a conveying screw such that the moving distance of toner is large, the deposition of toner is significant. Therefore, it is necessary to prevent toner from being widely deposited on the conveying screw.